For many years liquid fats have been aerated with a gas, such as air or nitrogen, to produce a plastic shortening. In the industry such aerated shortenings are known as plastic shortenings. They are called “plastic” as the shortening is in an easily deformable state without being fluid. A number of related processes have been used to create such aerated fats. In general, the liquid form of the fat and a gas, usually filtered air, are mixed, subjected to a high pressure, chilled and agitated to produce crystallization, and packaged. The primary utility of aerating the fat is in the improvement of the appearance of the shortening. An unaerated shortening has a yellowish, translucent appearance and is distinctly unappetizing to consumers. An aerated shortening, on the other hand, in which the gas is uniformly dispersed in very small bubbles, has a white opaque appearance which is very acceptable to consumers. In addition aerated shortenings are softer than unaerated shortenings and can be more easily creamed when they are being combined with other ingredients. However, while such plastic shortenings have been aerated for many years it is important to appreciate that the aeration of the fat provides little contribution to the development of air voids or air bubbles or air pockets in the dough or the final baked product produced with the aerated plastic shortening.
The standard methods for producing plastic shortenings involve heating the shortening to a temperature above the melting point of the solid components, rapidly chilling the liquid fat in a scraped surface heat exchanger to provide minute crystal nuclei, passing the cooled fat through a crystallizing unit in which crystallization can continue with mild agitation, and storage of the fat at a constant temperature in a final crystallization step called “tempering.” In one process, the aerating gas is injected into the fat prior to chilling, and the fat is maintained under high pressure during the chilling and crystallization stages to ensure that the injected gas is retained in solution. After the crystallization stage, the fat is passed through a throttle valve, also known as an extrusion valve, where the pressure on the fat is released and the dissolved gas comes out of solution and is dispersed in the fat as minute bubbles. The fat is then packed and maintained in a constant temperature room at about 80° F.-90° F. Other process methods have modified this basic process to shift the injection of gas to a point in the process that is after the crystallization stages. These types of processes are described in “Bailey's Industrial Oil and Fat Products,” Vol. 3, Thomas Applewhite, Ed.; Wiley-Interscience, New York, pages 101-103.
Processes for producing aerated shortening are described in the patents to Dalziel et al. U.S. Pat. No. 2,882,165 and Clarke U.S. Pat. No. 2,882,166. A process for producing an aerated shortening with a higher gas content is described in the patent to Kearns U.S. Pat. No. 3,095,305. These prior art processes operate at relatively high pressures, at least in the initial stages, primarily for the purpose of maintaining the gas in solution in the liquid fat. As indicated in the prior art, considerable difficulty has been encountered in obtaining a uniform product when using a relatively high level of gas.
Also, it has long been known that fatty substances could be cooled to a solid or semi-solid by applying a hot or warm liquid or semi-liquid of the fat to a cooled rotating drum or continuous cooling belt. In U.S. Pat. No. 788,446 to A. R. Wilson, a liquid fat is sprayed onto a rotating drum or cylinder which is cooled with ice or ice and salt. As the drum rotates, the previously applied liquid is scraped from the drum, and the scraped area of the drum is then subsequently presented for another application of the fat or liquid to be congealed. However, while these cooling processes are successful for many types of fats, they are unable to provide sufficient cooling during their cycle of operation to sufficiently chill fats and oils which have solids compositions which fall below the agglomeration boundary (line AB) of a Solids Fat Index such as is shown in FIG. 3. In such cases alternative flaking processes must be used.
FIG. 3 shows the solids content of a mixture of fats at various temperatures. The Solids Fat Index is a manufacturing standard used to measure the extent of hydrogenation in the fat components used in a mixture. Over a limited range, the Solid Fat Index (SFI) value is numerically, approximately equal to the actual percent solids in the mixture. At high temperatures, the fat product will be completely melted. At low temperatures, the fat can be completely solid. In between these low and high temperature ranges, there are varying degrees of solid fat content in the fat composition. By selection of varying degrees of hydrogenated triglycerides, and/or blended liquid and solid fats a variety of SFI profiles for various fat compositions can be developed.
For mixtures of hydrogenated triglycerides having solids compositions which fall below the agglomeration boundary, conventional chilled drum and chilled belt methods of flaking do not provide sufficient chilling time or sufficient temperature reduction in the mixture to: (1) produce sufficient nucleation in the fat mixture to allow flaking; (2) prevent the solidified fat from forming a sheet of material rather than flaking; and (3) reduce the temperature of the solidified material sufficiently to avoid re-melting of the material due to the latent heat of crystallization once the material is removed from the belt or roller and packaged.
Yet another drawback of the use of drum cooling for materials of the kind previously described is that when the melting point of the material becomes sufficiently low, generally 105° or below, the latent heat of crystallization will tend to be sufficient to virtually remelt the material or to cause the flakes or chips of the material to become a connected mass within the packaging material. Therefore, the use of rotating drum devices to cool materials having low melting points becomes ineffective, and triglycerides and other oils which have low melting points cannot be mixed with other substances which would have the effect of lowering the melting point of the triglyceride or the fatty substance to a point at which the drum cooling method would be ineffective as a result of the latent heat of crystallization causing the newly solidified material to form a mass once placed into packaging.
It will be appreciated by those skilled in the art that increasing retention time on the cooled rotating drum is an insufficient solution to this problem. Depending on the material being applied to the drum, if it is cooled too completely while on the drum, it will crack away from the drum and fall off the drum prior to it reaching the scraper blade or reaching a point at which collection of the material is desired. In certain types of drum cooling systems, the liquid is applied by the bottom of the drum rotating through a vat or pool of warmed liquid. The liquid then adheres to the drum and is cooled during the rotation of the drum, and the material is scraped from the drum prior to a second emersion in the vat of liquid. In this situation, slowing the drum can result in substantial loss of heat into the vat of hot or warm oil or triglyceride and can result in the heating of the material in the vat and the cooling of the drum operating at cross purposes.
To overcome this limitation of the drum cooling method a flat plate flaker device and method of operation has been developed. This flat plate flaker device is the subject of pending U.S. patent application Ser. No. 09/659,530 filed Sep. 12, 2000, and the contents of that application are incorporated herein by reference. As fully discussed in application Ser. No. 09/659,530, the flat plate flaker can provide adequate cooling for oils and oil blend for which the melting point of the material is sufficiently low, generally 105° or below, that the latent heat of crystallization will tend to be sufficient to virtually remelt the material or to cause the flakes or chips of the material to become a connected mass within the packaging material. Such a flat plate flake is of use with the process disclosed herein to cool oils and oil blends and, in particular, which exhibit such lower melting points.
The production of bakery goods which are light and fluffy and have a reduced fat content is another area of benefit which is provided by the inventions disclosed herein. Baked products are leavened by: (1) mixing air bubbles into the dough or batter in which the nucleating bubbles are then inflated by evolving and expanding gas; (2) carbon dioxide gas produced during yeast fermentation; (3) carbon dioxide gas produced by a reaction of a leavening acid with sodium bicarbonate or the heat decomposition of ammonium bicarbonate or ammonium carbonate; and/or (4) evaporation of water present in the dough and/or water present in “water in oil emulsion products during baking, commonly referred to as steam leavening.”
Generally, gas bubbles are formed only by mixing of the dough or stirring of the batter. The mixer blades create bubbles of air that are entrapped when the dough or batter is drawn into the cavity formed behind the blades. Carbon dioxide produced by the leavening reaction or fermentation then migrates into the nucleating bubbles that were formed during mixing. A large number of such small nucleating bubbles inflated to the desired volume will yield a find cell crumb structure with thin cell walls which is desirable in cakes and muffins. A smaller number of nucleating bubbles inflated to the same volume will result in a coarse crumb with large cells that have thick cell walls which is desirable in hearth breads, pizza crusts and English muffins.
When water is added to flour and physical work (mixing) is applied, glutenin and gliadin combine to form gluten which is the material primarily responsible for gas retention in the dough and for crumb structure. In bread products, gluten formation is critical to proper gas retention resulting in proper baked volume. Plastic shortening interferes with proper hydration and gluten formation, hence plastic shortening are used at lower levels. However, if a shortening could be added at higher levels and at the same time did not interfere with gluten formation, the baker could improve the texture, flavor and shelf life of the product without sacrificing product volume. This problem of interference with gluten formation can be avoided with a shortening product, such as a flaked fat, that does not interfere with gluten formation. A great benefit to baking could be achieved if such a flaked fat also could contribute nucleation bubbles to the dough without interfering with gluten formation. Also by adding an aerated fat flake, the baker could control the addition of nucleating air bubbles rather than relying solely on the degree of mixing. Also, by adding an aerated fat flake, the baker could create a desired texture by merely controlling the size of the aerated fat flake particle size.
The baking industry has long sought alternative methods of introducing air bubbles and air pockets into baked goods. The interests of the baking industry are diverse in this regard. In some products the amount of air captured and air space generated is valued in other products control over the timing of the generation of air bubbles or voids is of primary concern. In commercial and frozen baked goods in particular it is a primary interest that the means of generating air bubbles in the product be able to withstand long periods of freezing temperatures and then be able to produce the desired effect in the dough of generating air space or gas bubbles in the dough.
One means of providing such voids or bubbles in dough has been to incorporate a solid fat flake into the dough. Such solid fat flakes benefit the dough in two ways. First, by the inclusion of a fat in the dough improved the taste and mouth-feel of the dough or cooked crust are provided for the customer. Second, the solid fat flakes occupy space within the dough. When the dough is heated the fat flake melts and a void remains in the dough where the fat flake once existed. As will be appreciated, such solid flaked fats can withstand freezing temperature for long periods of time and still perform at the time of baking. Also, fat flakes do not require particularly special or critical handling during the dough mixing process other than being refrigerated.
In pizza dough, in particular, it has been recognized that solid flaked fats can be incorporated into the pizza dough at an amount of 8-12% (based on the dough flour weight) in addition to the regular oil. The presence of the flaked fat helps to create a desirable, open, course crumb structure in the finished pizza crust. The fat flakes are added to the pizza dough during the last few minutes of dough mixing so that the flakes retain their hard composition and integrity while being mixed into the dough. During the baking process the flakes melt and create the desired large voids in the crumb structure. A typical formula for a prior art self-rising pizza crust is shown in Table 3. (See, American Institute of Baking Research Department Technical Bulletin, Vol. XIX, Issue 11, November 1997.)
TABLE 1AmountBaker's PercentIngredient(based on flour = 100%)Flour100Salt1.75Sugar2Oil5Leavening Acid (SALP)0.75Baking Soda0.75Yeast (Compressed)0.25Water50Hard Fat Flakes (optional)8Reducing AgentAs Required
It will be appreciated by those skilled in the art that the size of the air space created by fat flakes in a dough is directly proportional to the size of the fat flake. Thus, with current fat flake products the only way to increase the amount of air incorporated into the dough is by increasing the amount of fat flake that is added to the mix. Additional fat flake can be undesirable for several reasons. The additional fat can affect the dough recipe, the additional fat can alter the nutritional values of the product, lower fat products are desired by the consumer and the use of additional fat increases costs.
Therefore, a great benefit could be derived by development of a flaked fat product which could act as an improved leavening agent to produce an air space in the dough which is greater than the space occupied by the fat flake itself. A further benefit is would be derived from such a product that did not require the increase in the amount of fat in the recipe to achieve such an increased air space. Another benefit to consumers and to manufacturers could be provided if the total amount of fat in the fat flake could be reduced while the same or increase air space is generated within the dough.
These benefits and more can be achieved by the present invention which provides a flaked fat leavening product and a method for the production of a flaked fat leavening agent which can increase the amount of air space generated in a dough during the baking of the dough and which reduces the amount of fat incorporated into the dough by the addition of the flaked fat product.
Previously, one such aerated flaked fat product has been made by a manual process. However, the resulting product only contained less than 12% by volume of air. Such a product was made by a hand process using a Hamilton Beach seven speed mixer, Model 585-3. During various experiments, oil at temperatures of between 80° F.-98° F. was placed into the blend and whipped at speed number 6 in the mixer. The oil could not be whipped for more than five minutes as the oil would begin to increase in temperature and to release the air which had become entrapped during mixing. The resulting mixture was then poured by hand onto a rotating drum cooler and the product flaked off the drum. The solid flaked shortening product contained less than 12% air by volume. This limited level of gas incorporation was deemed insufficient to provide the necessary cost savings required by manufacturers or to provide a sufficient increase in the amount of air which could be incorporated into baked dough products.